Abstract: A sheet collection mechanism includes three tray portions defining a slanted receiving surface. The surface extends from a lower stop against which sheets are stacked upward to a position below an egress for sheets and is long enough to stack long sheets without interference between the leading edge of an egressing sheet and the stack. To stack shorter sheets the downstream edges of two upper tray portions are selectively raiseable to cause the leading edge of a sheet to engage the stack downstream of the stacks' trailing edge. An auxiliary drive roller is positioned to cooperate with the downstream part of one of the upper trays when raised to assist in driving short sheets to the stop.